CVE-2022-2838 in Sphinx
Summary
by MITRE • 08/16/2022
In Eclipse Sphinx™ before version 0.13.1, Apache Xerces XML Parser was used without disabling processing of referenced external entities allowing the injection of arbitrary definitions which is able to access local files and expose their contents via HTTP requests.
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Analysis
by VulDB Data Team • 09/11/2022
The vulnerability identified as CVE-2022-2838 affects Eclipse Sphinx™ versions prior to 0.13.1 and represents a critical security flaw in XML processing that enables malicious actors to exploit external entity injection attacks. This issue stems from the improper configuration of the Apache Xerces XML Parser component within the Eclipse Sphinx environment, where external entity processing remains enabled despite the application's security requirements. The vulnerability manifests when the parser encounters XML documents containing external entity references that are not properly sanitized or restricted, creating an attack surface that allows for unauthorized data access and potential information disclosure.
The technical implementation of this vulnerability involves the exploitation of XML External Entity (XXE) processing capabilities within the Xerces parser. When Eclipse Sphinx processes XML content, it fails to disable the resolution of external entities, which allows attackers to craft malicious XML payloads that reference external resources. These references can be crafted to point to local files on the server filesystem, enabling attackers to read sensitive data from arbitrary locations. The vulnerability is particularly dangerous because it leverages HTTP requests to exfiltrate the contents of local files, making it possible for attackers to access configuration files, user data, or other sensitive information stored on the system.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a potential vector for more severe attacks including local file inclusion, remote code execution, and denial of service conditions. Attackers can leverage the ability to read local files to gather system information, access credentials stored in configuration files, or identify other vulnerabilities within the system. The attack requires minimal sophistication as it only requires the ability to submit XML content to the affected application, making it particularly dangerous in environments where XML processing is common or where users can upload content. This vulnerability directly maps to CWE-611 Information Exposure Through XML External Entity Reference and aligns with ATT&CK technique T1059.007 for XML External Entity Injection, which is categorized under the broader category of information gathering and initial access.
Mitigation strategies for this vulnerability require immediate patching of the Eclipse Sphinx application to version 0.13.1 or later, which includes proper configuration of the Xerces parser to disable external entity processing. Organizations should also implement strict input validation and sanitization for all XML content processed by the application, ensuring that external entity declarations are rejected or properly escaped. Additional defensive measures include network segmentation to limit access to the affected systems, implementing web application firewalls to detect and block malicious XML payloads, and conducting regular security assessments to identify similar vulnerabilities in other XML processing components. The fix should ensure that XML parsers are configured with secure defaults that disable external entity resolution and DTD processing, aligning with industry best practices for secure XML processing as recommended by OWASP and NIST guidelines.